Rotative winged aircraft



April 11, 1939- H. s. CAMPBELL 2,153,610

KOTATIVE WINGED AIRCRAFT Filed Nov. 13, 1955 5 Sheets-Sheet l INVENTORBY WV MW ATTORNEY' April 11, 1939. H. s. CAMPBELL ROTATIVE WINGEDAIRCRAFT Filed Nov. 15, 1935 3 Sheets-Sheet 2 ATTORNEY5 April 1939- H.s. CAMPBELL 2,153,610

ROTATIVE WINGED AI RGRAFT Filed NOV. 13, 1955 3 Sheets-Sheet 5' INVENTORj ATTORN EYS Patented Apia-11, 1939 s PATENT OFFICE BOTATIVE WINGEDAIRCRAFT Harris 8. Campbell, Willow Grove, Pa., assignor, by mesneassignments, to Autogiro Company of America, a corporation of DelawareApplication November 13, 1935, Serial No. 49,451

11 Claims.

This invention relates to aircraft of the type having a sustaining rotorcomposed of a plurality of blades articulated to a hub mechanism, therotor being actuable by relative airflow in flight. The invention ismore particularly concerned with the mounting of the blades and controlmeans for craft of this type, especially with that general type ofcontrol providing for shift of the lift line of the rotor with referenceto the center of gravity of the machine so as to produce tiltingmoments. With the above in view, the present invention contemplates amounting and control arrangement for a sustaining rotor in accordancewith which the blades of the rotor are mounted for oscillative movementssubstantially about their longitudinal axes so as to vary the pitch, andin accordance with which control means are provided for producing aperiodic change in the pitch of the blades during rotation of the rotor.

The invention has in view an improved mounting and control system of thetype referred to, the same being not only of simple and ruggedconstruction but also capable of compact arrangement.

More particularly, the invention contemplates the employment ofarticulations for the blades providing for swinging movements thereof inpaths generally transverse the rotative path of travel, and also forpitch change movements thereof, the articulations for the latter purposebeing located inboard of the articulations for the swinging movements.In this way, changes in pitch of the blades does not alter the angle ofswinging thereof with respect to the chord line.

A further object of the invention is involved in the provision of asimplified control mechanism, this end being served by virtue ofthearrangement of pivots just mentioned, it being pointed out that thecontrol connections cooperate with blade parts located inboard of thepivots providing for swinging movements of the blades transverse theirrotative path of travel, in consequence of which the control connectionsneed not be made to accommodate or compensate for the said swingingmovements of the blades.

How the foregoing objects and advantages are attained, together withothers which will occur to those skilled in the art, will be moreapparent from a consideration of the following description referring tothe accompanying drawings, in which Figure 1 is a vertical longitudinalsectional view through a rotor head or hub mechanism constructed inaccordance with this invention;

Figure 2 is a rear view of the structure of Fig.-

ure 1 with certain parts shown in elevation and others in verticalsection;

Figure 3 is a top plan view of the mechanism shown in Figures 1 and 2;

.Figure 4 is a view similar to Figure 1 but show ing a modifiedarrangement; and

Figure 5 is a composite sectionalview taken substantially as indicatedby the, section line 5-5 of Figure 4.

In the arrangement of Figures 1, 2 and 3, I 10 have illustrated amechanism suitable for use with a sustaining rotor having an even numberof blades, preferably four, the root ends of these blades being shown at6. The blades and the hub structure therefor are preferably supported 15above'the body of the craft as by means of a pair of forward pylon legs1-1 and a centrally located rear pylon leg 8, the three legs forming atripod joined, as by sleeves 9, to an apex box I 0. This box mayconveniently be split horizontally as at 20 II for purposes of assemblyand the like and is provided with sockets to receive the verticallyspaced bearings l2 which serve to journal the tubular spindle I 3. Aflanged and threaded collar H at the bottom of the spindle I3 serves totrans- 25 mit the thrust of sustension from the rotor to and through thelower bearing I2 from which it is carried through the apex casing ill tothe pylon legs I and 8.

The spindle l3 projects above the upper bearing 30 I2 for the attachmentof the blades thereto in the manner to be described hereinafter. Withinthe casing ID the spindle I3 preferably carries a sleeve l5 splined orotherwise secured thereto, this sleeve in turn serving to carry the druml6 formed on its inner surface as a brake drum to cooperate with thebrake parts H. An external ring gear I8 is also carried by the drum it,an over-running or free-wheeling device i 9 being interposedtherebetween. A pinion 20 housed and journalled in an extension 2| ofthe casing I0 meshes with the ring gear l8 and serves to deliver torqueto the rotor for starting or other purposes. The pinion 20 may, ofcourse, be driven by shaft 22 extending downwardly between the twoforward pylon legs I for connection with the engine provided for forwardpropulsion of the craft.

As best seen in Figure 3, toward its upper end the hollow spindle I3 ispreferably squared to provide a number of flattened portions equivalentto the number of blades to be attached. Each side of the squared part isapertured and provided with a recess for a bearing 23. Opposed pairs ofthese bearings cooperate with each other inproviding a rotative mountingfor a member traversing the hub and projecting from each side thereoffor attachment of a pair of blades. One of these members, 24, isprovided with a centrally apertured yoke 25, the aperture of which issomewhat larger in diameter than the transverse member 26 for the otherpair of blades which passes therethrough, this latter member beingjournalled in the other pair of bearings 23. By virtue of the enlargedaperture in the eye 25, both of the members 24 and 26 may freely rocksomewhat about the axes of their pairs of bearings 23-23.

For convenience in assembly and the like, each end of each of themembers 24 and 26 is threaded as at 21 to receive a blade pivot part 28which latter may also be pinned to the threaded part 21 as indicated at29. Each pivot part 28 is apertured to receive the pivot pin 38 whichserves to couple part 28 with a forked part or extension link 3|. Theextension link in turn is connected by a pivot 32 with a forked fitting33 at the root end of the blade 6. These pivots 30 and 32 providefreedom for force compensating movements of the blade in two planes, thefirst (30) permitting freedom for swinging of the blades generallytransverse of their rotative path of travel and the second (32)permitting freedom for swinging movements fore and'aft in the generalpath of travel. The blades may be supported as against excessivedownward droop about the pivots 36 by means of supporting cables 34connected to the blades at a point spaced outwardly from the pivots andalso connected with a cone or similar support 35 mounted at the top ofthe hub member I3.

For the purpose of controlling movement of the blades to vary' the pitchthereof, 1. e., movement about the axes of bearings 23-23, I employ acontrol member 36 having four prongs 31 projecting upwardly therefrom toembrace the members 24 and 26 at their point of intersection. Theseforks 31 engage fiatted portions or surfaces formed at opposite sides ofeach of the members 24 and 26 so that upon tilting of the control lever36 one or the other or both pairs of blades are caused to change theirpitch. The

upper ends of the forks 31 are preferably tied together by a member 38,studs 39 being provided for this purpose. The part 38 has its lowersurface curved to fit and bear on the upper curved surface of the eye 25in member 24.

The control arm 36 projects downwardly within the hollowed hub andpreferably extends below the lower end of the hub, at which point itcarries a non-rotating sleeve 40 within which the member 36 is free torotate. Pairs of yokes 4| are pivoted to sleeve 40 as at 42 and eachyoke serves for connection with a control cable 43. By virtue of thisassembly the lever 36 may be tilted in any desired direction, the collar40 and the associated yokes 4| remaining stationary while the controlelement itself (36) rotates with the rotor. The control cables mayconveniently be carried downwardly toward the body of the craft, pulleys44 for this purpose being mounted on the-pylon legs 1 and 8. As alsoseen by comparison of Figures 1 and 2, one of the control cables 43 iscarried downwardly within the single rear pylon leg 8. cable is carrieddown between the two forward legs, a bracket 45 being provided for theguide pulley therefor. The two remaining cables,

which extend from the control element laterally toward opposite sides ofthe craft, are turned in a forward direction about the pulleys 46, afterwhich these cables pass over pulleys 43 mounted The diametricallyopposite.

on the two forward pylon legs 1-1 and extend therethrough toward thebody of the craft.

From the foregoing it will be seen that by the structure of Figures 1 to3 inclusive I have made possible the attainment of a number ofadvantages including the following:

The members 24 and 26 which interconnect opposed blades constitutingpairs, serve to carry centrifugal loads directly from blade to bladeacross the rotor instead of through the hub itself. Still further, thearrangement while providing the foregoing, alsopermits location of allthe blades of a four-bladed rotor in the same horizontal plane.

The control system is of especial advantage because of its arrangementand location, particularly with reference to the several-bladearticulations. Note that the pivot for pitch change of the blades isdisposed inboard not only of the horizontal pivots 30 but also of thedrag pivots 32. In addition, note that the control lever 36 cooperateswith the tie members between opposed pairs of blades within the hubitself. Such an arrangement not only simplifies the structure because ofthe compactness of effective utilization of space, but further for thereason that when connected in this manner the control system need not bedesigned to accommodate swinging movements of the blades either aboutthe flapping pivots 30 or the drag pivots 32. Thus it is of advantagethat the pitch change pivot be disposed inboard of other bladearticulations, and further that the connection of the control lever withthe blades be made centrally within the hollow hub.

A still further advantage of the construction described is that eventhough the number of bearings providing an axis for pitch changemovements is equal only to the number of blades in the rotor, still abroad base is afforded by the pairs of these bearings.

In operation, the control cables 43 are, of course, actuated by asuitable mechanism within the body of the craft, such as the usualcontrol lever, the hook-up of these cables being such as to provide forperiodic pitch change of the blades in response to control membermovements in the senses provided for in accordance with the copendingapplication of Juan de la Cierva, Serial No. 698,372, filed November 16,1933. As to the general nature and functioning of the control system, itmay here be briefly stated that by movement of the control lever in thebody of the craft in a forward direction and the consequent movement ofthe control element 36, the blades are caused to periodically changetheir incidence during the cycle of rotation in that sense whichproduces rearward displacement of the lift line with 'reference to thecenter of gravity of the craft.- This, of course, produces a nose-downmoment and the control thus retains the instinctive control movementscommonly adopted in aircraft practice. The case is similar with respectto transverse movements of the control stickin the body of the craft inlateral directions so as to produce banking moments and, in addition,for any combinations of control stick movements.

As a result of tilting the control element 36, of course (for example ina forward direction or to the left as viewed in Figure 1), the pitch ofthe blades in the fore and aft positions is not affected althoughthepitch of the blades in the transversepositions' is changed. With a rotorturning counterclockwise when viewed in top plan, a forward movement ofthe control element 36 increases the pitch of the blade on the advancingside and decreases the pitch of the blade on the retreating side.Lateral and compound move ments of the control element 36 may also betraced out in a similar manner.

Turning now to the arrangement'shown in Figures 4 and 5, it is firstpointed out that this structure is particularly adapted for use with arotor having an odd number of blades, for example, a three-bladed rotoras shown. The three blades are indicated by the numerals 41. The hubmember to which these blades are attached again takes the form of atubular spindle, here designated by the numeral 48, this spindle beingmounted in bearings 49 carried in a sleeve 50 which is supported bysuitable struts or the like The upper portion 52 of the hub member 48 inthis case is also formed with flatted portions, certain of whichcooperate with the three blades. In contrast with the arrangement ofFigures 1 to 3 inclusive, the three-bladed structure provides forindividual attachment of the blades to the hub part 52. For each bladean attachment device 53 is arranged to project through an aperture inthe hub part 52, this device having a threaded part 54 adapted tocooperate with member 55 which is journalled as by bushing 56 in the hubpart 52 and projects outwardly therethrough to cooperate with the pivot51 serving to couple member 55 with the forked blade root fitting 58.Each device 53 is provided with a shoulder or flange 59 for transmittingcentrifugal loads of the blade to the hub part 52. Thus the blades areprovided with articulations permitting freedom for swinging movementthere of in paths generally transverse the mean rotative path of traveland, in addition, for movement substantially about their longitudinalaxes to vary the pitch. With a view to supporting the blades when theyare at rest or not rotating at flight speeds, I provide telescopicmembers 12 and 13 which interconnect the blades and a standard 14 at thetop of the hub by means of pivots l5 and 16. A pin 11 secured to theinside member 12 and working in slot 18 in the outside member 13 servesto arrest downward movement of the blades on their flapping pivots 51.The member 12 is further mounted for rotation at 19 with respect to theend fitting 80 which is coupledito the blade, this freedom for movementbeing provided so as not to interfere with oscillation of the bladessubstantially about their longitudinal axes.

The member 53 for each blade is further provided with an inwardprojection 60 having flatted sides embraced by the fork parts Bl-6I oflinks 62 which depend therefrom for connection with the co trol element63. At the upper end of each link 62 the fork parts 6| are preferablypinned as at 64 to the inner projection 60 of one of the blades. Attheir lower ends, the links 62 are similarly forked and the fork parts65-65 embrace a joint block 66 which in turn is pivoted by a pin 81 toirs of apertured lugs 68 carried on the control Rlement 63.

As in he arrangement of Figures 1 to 3, the control element ispreferably carried down to a level below the bottom of the hub member 48and a ring 69 is mounted on the lower end thereof by a bearing I0.Control cables ll arranged in pairs at right angles to each other areattached to the ring 69 so as to provide for movement thereof in anydesired direction.

The control members 60 to 68 inclusive, as described above, constitute aparallel linkage permitting freedom for swinging movement of the controlelements 68 either fore or aft, or from side to side, or in otherdirections representing a compound movement. It will be noted that whilea given horizontal plane in the control element 63 will rise somewhatduring swinging thereof in any direction, still this plane will remainhorizontal, and in operation movement of the control element G3 in oneazimuth will not affect the pitch of the blades as they pass throughthat azimuth or through the azimuth diametrically opposite thereto, butwill change the pitch of the blades as they pass through the twoazimuths at right angles to the direction of movement. To furtherillustrate this operation, assume a movement of the control element 63to the left as viewed in Figure 4. It will readily be seen that thismovement will not affect the incidence of the forward blade 41 (at theleft), but will change the inci dence of the two blades positioned 120from the forward position. The degree to which the pitch of the bladesis affected (upon a movement of the control element 63 to the left) willvary from a minimum in the fore and aft positions to a maximum in thetwo transverse positions. Assuming a rotor rotating counterclockwisewhen viewed in top plan, a forward displacement of the control element63 effects an increase of the pitch of the blades as they are advancingand a decrease of the pitch as they are retreating.

By virtue of the arrangement of Figures 4 and 5, therefore, I have madepossible the control of pitch of the blades of a three-bladed rotor in amanner to permit periodic pitch change throughout the cycle of rotationand thus shift of the lift v line with respect to the center of gravityof the craft for control purposes. In addition, numerous of theadvantages mentioned above in connection with Figures 1 and 3 inclusiveare also realized in the three-bladed arrangement, it being notedparticularly that the structure is outstanding in compactness andsimplicity, this latter purpose again being served by virtue of controlconnections which do not necessitate the use of any means foraccommodating swinging movements of the blades about their flappinghinges 51. It will be understood that while I have not illustrated dragarticulations for the blades in the arrangement of Figures 4 and 5,these may readily be adopted as in the construction of Figures 1 to 3.

I claim:

1. For an aircraft sustaining rotor having a plurality of blades, ahollowed hub member, a mechanism for connecting the blades with the hubmember including pivot means providing for oscillation of the bladessubstantially about their longitudinal axes to vary the pitch thereof,and a control mechanism for periodically varying the pitch of the bladesduring rotation thereof, said control mechanism including a controlelement offset from the plane of attachment of the blades to the hubmember, and parallel links in said hollowed hub member individuallyinterconnecting the blades with the control element.

2. For an aircraft sustaining rotor having a plurality of blades and ahub member, a mechanism for connecting the blades with the hub memberincluding pivot means providing for oscillation of the bladessubstantially about their longitudinal axes to vary the pitch thereof,and a control mechanism for differentially varying the pitch of theblades during rotation thereof, said control mechanism including acontrol element movable in a direction generally transverse the axis ofthe rotor, and parallel links interconnecting the control element andthe blades, said links being pivoted to the blade for swinging movementin one direction and being universally jointed to the control element.

3. For an aircraft sustaining rotor having at least three blades, acentrally apertured hub member, pivot *means for connecting the bladesto the hub member including, for each blade, a pivot providing foroscillation of the blade substantially about its longitudinal axis, theblades further having parts projecting into the aperture of said hubmember, and control mechanism for periodically varying the pitch of theblades during rotation thereof including a control element offset fromthe plane of said parts, and links pivotally and individuallyinterconnecting said parts with the control element.

4. For an aircraft sustaining rotor having at least three blades, acentrally apertured hub member, pivot means for connecting the blades tothe hub member including, for each blade, a pivot providing foroscillation of the blade substantially about its longitudinal axis, theblades further having parts projecting into the aperture of said hubmember, and control mechanism for periodically varying the pitch of theblades during rotation thereof including a control element movable in adirection generally transverse the axis of the rotor and offset from theplane of said parts, and links pivotally interconnecting the controlelement and said parts, each link being universally jointed to thecontrol element and being connected with one of said parts for pivotalmovement in at least one sense.

5. For an aircraft sustaining rotor having a plurality of blades and ahub member, a mechanism for connecting the blades with the hub memberincluding pivot means providing for oscillation of the bladessubstantially about their longitudinal axes to vary the pitch thereof,and a control mechanism for periodically varying the pitch of the bladesduring rotation thereof, said control mechanism including a controlelement movable in a direction generally transverse the axis of therotor, and parallel links interconnecting the control element and theblades, said links being pivoted to the blade for swinging movement inone direction and being universally jointed to the control element, thecontrol element and links being rotatable with the rotor, a collar inwhich the control element is rotatively mounted, and actuating meanscooperating with said collar to displace the control element.

6. For an aircraft sustaining rotor having at least four blades, pivotmeans interconnecting the blades in pairs, the pivot means of each pairproviding for rotation of the blades substantially about theirlongitudinal axes to vary the pitch thereof, all of said pivot meansbeing arranged to intersect substantially in a common horizontal planeand having flatted parts adjacent the point of intersection, and meansfor controllably varying the pitch of the blades including a controlmember having a plurality of fork elements engaging said flatted parts,whereby to effect oscillation of the blades in pairs substantially abouttheir longitudinal axes.

7. For an aircraft sustaining rotor having a hub and a plurality ofblades, pivot means interconnecting the blades, the pivot means of eachpair providing for rotation of the blades substantially about theirlongitudinal axes to vary the pitch thereof, all of said pivot meansbeing arranged to intersect substantially in a common horizontal plane,and means for controllably varying the pitch of the blades including acontrol member having a plurality of fork elements embracing the pivotmeans adjacent the point of intersection thereof, whereby to effectoscillation of the blades in pairs substantially about theirlongitudinal axes.

8. For an aircraft sustaining rotor having a plurality of blades, anapertured hub member, means for connecting the blades with the hubmember including, for each blade, a mounting pivot positioned with itsaxis generally in alignment with the longitudinal axis of the blade,said pivot being journalled in the hub member and.

1 having a flatted portion projecting into the aperture of the hubmember, and means for effecting a periodic change of pitch of the bladesduring rotation thereof'including a control member engaging the fiattedportions of the projections in said aperture.

9. For an aircraft sustaining rotor having at least four blades, pivotmeans interconnecting the blades in pairs, the pivot means of each pairproviding for rotation of the blades substantially about theirlongitudinal axes to vary the pitch thereof, all of said pivot meansbeing arranged to intersect substantially in a common horizontal planeand having flatted parts adjacent the point of intersection, and meansfor controllably varying the pitch of. the blades including I and intothe interior thereof, the pivot member being journaled in the side wallof the hub for rotation about an axis generally in alignment with thelongitudinal axis of the blade to pro vide freedom for pitch variationof the blade, and control mechanism for periodically varying the pitchof the blade during rotation of the rotor 1, including control meansvertically offset from the plane of the blade and movable in anydirection in a generally horizontal plane, and a substantially verticallink interconnecting said last means and the portion of the pivot devicewhich projects into the hollowed hub, the con nection of said link andsaid pivot device providing freedom for relative angling of said twoparts in a generally vertical plane containing the longitudinal axis ofthe blade but restraining relative movement of said two parts in a planeperpendicular to the longitudinal axis of the blade.

11. In a bladed aircraft sustaining rotor, a hollowed hub structure,means for mounting a blade on the hub including a pivot memberprojecting through a side wall of the hollowed hub and into the interiorthereof, the pivot member being journaled in the side Wall of the hubfor rotation about an axis generally in alignment with the longitudinalaxis of the blade to provide freedom for pitch variation of the blade,and control mechanism for varying the pitch of the blade includingcontrol means vertically downwardly offset from the plane of the bladeand its mounting pivot below the lower end of the hollowed hub, thecontrol means being movable in any direction in a generally horizontalplane, and a substantially vertical link interconnecting said last meansand the portion of the pivot device which projects into the hollowedhub, the connection of said link and said pivot device providing freedomfor relative angling of said two parts in a generally vertical planecontaining the longitudinal axis of the blade but restraining relativemovement of said two parts in a plane perpendicular to the longitudinalaxis of the blade. HARRIS S. CAMPBELL.

